Microbial communities in developmental stages of lucinid bivalves

Abstract

Bivalves from the family Lucinidae host sulfur-oxidizing bacterial symbionts, which are housed inside specialized gill epithelial cells and are assumed to be acquired from the environment. However, little is known about the Lucinidae life cycle and symbiont acquisition in the wild. Some lucinid species broadcast their gametes into the surrounding water column, however, a few have been found to externally brood their offspring by the forming gelatinous egg masses. So far, symbiont transmission has only been investigated in one species that reproduces via broadcast spawning. Here, we show that the lucinid Loripes orbiculatus from the West African coast forms egg masses and these are dominated by diverse members of the Alphaproteobacteria, Clostridia, and Gammaproteobacteria. The microbial communities of the egg masses were distinct from those in the environments surrounding lucinids, indicating that larvae may shape their associated microbiomes. The gill symbiont of the adults was undetectable in the developmental stages, supporting horizontal transmission of the symbiont with environmental symbiont acquisition after hatching from the egg masses. These results demonstrate that L. orbiculatus acquires symbionts from the environment independent of the host’s reproductive strategy (brooding or broadcast spawning) and reveal previously unknown associations with microbes during lucinid early development.

Extracellular chemosymbiont populations in a shallow-water thyasirid clam potentially shaped by priority effect

“…Most other hosts, however, use horizontal transfer where they acquire symbionts from the environmental pool post-settlement. Horizontal acquisition is typified by a more diverse symbiont community, with the absence of symbionts in gonads and at the larval stages, and also the inconsistent or even disordered phylogeny between host and symbiont seen in bathymodioline mussels [12, 30, 31], lucinid clams [32], and Alviniconcha snails [33]. A mixed mode of the above two acquisition modes has been proposed in solemyid clams and the peltospirid snail Chrysomallon squamiferum [34, 35].…”

Fish and fisheries dynamics at Banc d'Arguin, Mauritania: consequences for the intertidal food webs

“…The bivalve family of Lucinidae including Loripes sp. engages in a beneficial mutualistic relationship with seagrass (de Fouw et al, 2016b;van der Heide et al, 2012b;Zauner et al, 2022).…”